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Comments on How can I modify the code above to accept string as user input and use strcmp to compare with the contents of the text file & then delete that line?

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How can I modify the code above to accept string as user input and use strcmp to compare with the contents of the text file & then delete that line?

+1
−4

I want to enter a string to compare with the text file, and if that word matches, then I want to delete that line containing that string. How can I modify the code below, since the code below takes line number as input to delete a specific line. Thank you.

#include <stdio.h>
    
int main()
{
    FILE *fileptr1, *fileptr2;
    char filename[40];
    char ch;
    int delete_line, temp = 1;
    printf("Enter file name: ");
    scanf("%s", filename);
    //open file in read mode
    fileptr1 = fopen(filename, "r");
    ch = getc(fileptr1);
    while (ch != EOF)
    {
        printf("%c", ch);
        ch = getc(fileptr1);
    }
    //rewind
    rewind(fileptr1);
    printf(" \n Enter line number of the line to be deleted:");
    scanf("%d", &delete_line);
    //open new file in write mode
    fileptr2 = fopen("replica.c", "w");
    ch = 'A';
    while (ch != EOF)
    {
        ch = getc(fileptr1);
        //except the line to be deleted
        if (temp != delete_line)
        {
            //copy all lines in file replica.c
            putc(ch, fileptr2);
        }
        if (ch == '\n')
        {
            temp++;
        }
    }
    fclose(fileptr1);
    fclose(fileptr2);
    remove(filename);
    //rename the file replica.c to original name
    rename("replica.c", filename);
    printf("\n The contents of file after being modified are as follows:\n");
    fileptr1 = fopen(filename, "r");
    ch = getc(fileptr1);
    while (ch != EOF)
    {
        printf("%c", ch);
        ch = getc(fileptr1);
    }
    fclose(fileptr1);
    return 0;
}

Example of contents in text file: hello world up one two three User input: hello Updated contents in text file: one two three

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3 comment threads

ch needs to be int (1 comment)
Does it really need to be words (in the lexical sense)? (1 comment)
Why is your question quoted? (3 comments)
Does it really need to be words (in the lexical sense)?
elgonzo‭ wrote over 2 years ago · edited over 2 years ago

Don't make your life more difficult than you have to. Do you really want to find a word (in the orthographic sense) in some text line of your text file? At your current skill level, this would not be trivial for you, a fountain of frustration and a distraction rife with disappointment.

Searching for words means accounting for word boundaries.

For example, the line hello world up clearly and obviously contains the words "hello", "world" and "up".

But hello world up does not contain the word "hell". And yet, "hell" does actually appear in the text line, despite it not being any of the words the text line is made of.

"How now, brown cow?"

So, stop looking for words. Just don't do it. Instead, change your requirements to find occurrences of sub-strings in the lines of your text file - a task much easier to accomplish.

Any C tutorial about string operations (at least those worthy of the name "tutorial") will teach you how to find sub-strings in a given string.

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